I didn't see anyone asking what kind of radio you are using. Not all radios lend themselves to things like Flaperons or spoilerons. Using A Y-harness kinda works but it leaves A lot left to be desired.
If you install your aileron servos about mid way on each wing half your servo isn't working as hard and it is holding better. You will also need extensions for the wires and make up paper tubes for the wires to run through so you can get things in and out through the wing ribs.
There is A bit more to installing two elevator and/or aileron servos then just mounting them but it's pretty simple.
I have just finished teaching my youngest student the art of building and we are ready to finish sand and cover his nice little 4*60. We did do A few mods but nothing very much, just A bigger rudder and clipped the wings. We reinforced the LG block and I just happened to have A better set of LGs for it.
I love the 4* series and it's A great learning tool plus A good flying plane.
Good luck!!